tencent cloud

简介

本文档提供关于对象的下载操作相关的 API 概览以及 SDK 示例代码。

简单操作

高级接口（推荐）

下载对象（断点续传）

功能说明

分块下载接口根据用户对象的长度，自动使用 Range 下载数据，实现并发下载，分块大小默认1048576（1MB），可通过 part_size 参数调整。

方法原型

cos_status_t *cos_resumable_download_file(cos_request_options_t *options,
                                        cos_string_t *bucket,
                                        cos_string_t *object,
                                        cos_string_t *filepath,
                                        cos_table_t *headers,
                                        cos_table_t *params,
                                        cos_resumable_clt_params_t *clt_params,
                                        cos_progress_callback progress_callback);

参数说明

结果说明

示例

#include "cos_http_io.h"
#include "cos_api.h"
#include "cos_log.h"
// endpoint 是 COS 访问域名信息，详情请参见 https://www.tencentcloud.com/document/product/436/6224 文档
static char TEST_COS_ENDPOINT[] = "cos.ap-guangzhou.myqcloud.com";
// 开发者拥有的项目身份ID/密钥，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char *TEST_ACCESS_KEY_ID;                //your secret_id
static char *TEST_ACCESS_KEY_SECRET;            //your secret_key
// 开发者访问 COS 服务时拥有的用户维度唯一资源标识，用以标识资源，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char TEST_APPID[] = "<APPID>";    //your appid
//the cos bucket name, syntax: [bucket]-[appid], for example: mybucket-1253666666，可在 https://console.tencentcloud.com/cos5/bucket 查看
static char TEST_BUCKET_NAME[] = "<bucketname-appid>";
static char TEST_DOWNLOAD_NAME4[] = "multipart_download.dat";
static char TEST_MULTIPART_OBJECT4[] = "multipart4.dat";
void log_status(cos_status_t *s)
{
  cos_warn_log("status->code: %d", s->code);
  if (s->error_code) cos_warn_log("status->error_code: %s", s->error_code);
  if (s->error_msg) cos_warn_log("status->error_msg: %s", s->error_msg);
  if (s->req_id) cos_warn_log("status->req_id: %s", s->req_id);
}
void init_test_config(cos_config_t *config, int is_cname)
{
  cos_str_set(&config->endpoint, TEST_COS_ENDPOINT);
  cos_str_set(&config->access_key_id, TEST_ACCESS_KEY_ID);
  cos_str_set(&config->access_key_secret, TEST_ACCESS_KEY_SECRET);
  cos_str_set(&config->appid, TEST_APPID);
  config->is_cname = is_cname;
}
void init_test_request_options(cos_request_options_t *options, int is_cname)
{
  options->config = cos_config_create(options->pool);
  init_test_config(options->config, is_cname);
  options->ctl = cos_http_controller_create(options->pool, 0);
}
void test_resumable()
{
  cos_pool_t *p = NULL;
  int is_cname = 0;
  cos_status_t *s = NULL;
  cos_request_options_t *options = NULL;
  cos_string_t bucket;
  cos_string_t object;
  cos_string_t filepath;
  cos_resumable_clt_params_t *clt_params;

  cos_pool_create(&p, NULL);
  options = cos_request_options_create(p);
  init_test_request_options(options, is_cname);
  cos_str_set(&bucket, TEST_BUCKET_NAME);
  cos_str_set(&object, TEST_MULTIPART_OBJECT4);
  cos_str_set(&filepath, TEST_DOWNLOAD_NAME4);
   clt_params = cos_create_resumable_clt_params_content(p, 5*1024*1024, 3, COS_FALSE, NULL);
  s = cos_resumable_download_file(options, &bucket, &object, &filepath, NULL, NULL, clt_params, NULL);
  log_status(s);
   cos_pool_destroy(p);
}
int main(int argc, char *argv[])
{
  // 通过环境变量获取 SECRETID 和 SECRETKEY
  TEST_ACCESS_KEY_ID     = getenv("COS_SECRETID");
  TEST_ACCESS_KEY_SECRET = getenv("COS_SECRETKEY");
    if (cos_http_io_initialize(NULL, 0) != COSE_OK) {
     exit(1);
  }
   //set log level, default COS_LOG_WARN
  cos_log_set_level(COS_LOG_WARN);
   //set log output, default stderr
  cos_log_set_output(NULL);
   test_resumable();
   cos_http_io_deinitialize();
   return 0;
}

批量下载（从 COS 下载目录）

功能说明

将 COS 目录及其文件下载到本地磁盘。

示例

#include "cos_http_io.h"
#include "cos_api.h"
#include "cos_log.h"
// endpoint 是 COS 访问域名信息，详情请参见 https://www.tencentcloud.com/document/product/436/6224 文档
static char TEST_COS_ENDPOINT[] = "cos.ap-guangzhou.myqcloud.com";
// 开发者拥有的项目身份ID/密钥，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char *TEST_ACCESS_KEY_ID;                //your secret_id
static char *TEST_ACCESS_KEY_SECRET;            //your secret_key
// 开发者访问 COS 服务时拥有的用户维度唯一资源标识，用以标识资源，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char TEST_APPID[] = "<APPID>";    //your appid
//the cos bucket name, syntax: [bucket]-[appid], for example: mybucket-1253666666，可在 https://console.tencentcloud.com/cos5/bucket 查看
static char TEST_BUCKET_NAME[] = "<bucketname-appid>";
void log_status(cos_status_t *s)
{
  cos_warn_log("status->code: %d", s->code);
  if (s->error_code) cos_warn_log("status->error_code: %s", s->error_code);
  if (s->error_msg) cos_warn_log("status->error_msg: %s", s->error_msg);
  if (s->req_id) cos_warn_log("status->req_id: %s", s->req_id);
}
void init_test_config(cos_config_t *config, int is_cname)
{
  cos_str_set(&config->endpoint, TEST_COS_ENDPOINT);
  cos_str_set(&config->access_key_id, TEST_ACCESS_KEY_ID);
  cos_str_set(&config->access_key_secret, TEST_ACCESS_KEY_SECRET);
  cos_str_set(&config->appid, TEST_APPID);
  config->is_cname = is_cname;
}
void init_test_request_options(cos_request_options_t *options, int is_cname)
{
  options->config = cos_config_create(options->pool);
  init_test_config(options->config, is_cname);
  options->ctl = cos_http_controller_create(options->pool, 0);
}
void test_download_directory()
{
  cos_pool_t *p = NULL;
  int is_cname = 0;
  cos_status_t *s = NULL;
  cos_request_options_t *options = NULL;
  cos_string_t bucket;
  cos_string_t file_name;
  cos_string_t suffix = cos_string("/");
  cos_table_t *resp_headers;
  cos_table_t *headers = NULL;
  cos_table_t *params = NULL;
  int is_truncated = 1;
  cos_string_t marker;
  apr_status_t status;
   //初始化请求选项
  cos_pool_create(&p, NULL);
  options = cos_request_options_create(p);
  init_test_request_options(options, is_cname);
  cos_str_set(&bucket, TEST_BUCKET_NAME);
   //list object (get bucket)
  cos_list_object_params_t *list_params = NULL;
  list_params = cos_create_list_object_params(p);
  cos_str_set(&list_params->prefix, "folder/");   //替换为您自己的目录名称
  cos_str_set(&marker, "");
  while (is_truncated) {
      list_params->marker = marker;
      s = cos_list_object(options, &bucket, list_params, &resp_headers);
      log_status(s);
      if (!cos_status_is_ok(s)) {
          printf("list object failed, req_id:%s\n", s->req_id);
          break;
      }
      cos_list_object_content_t *content = NULL;
      cos_list_for_each_entry(cos_list_object_content_t, content, &list_params->object_list, node) {
          cos_str_set(&file_name, content->key.data);
          if (cos_ends_with(&content->key, &suffix)) {
              //如果是目录需要先创建, 0x0755权限可以自己按需修改，参考apr_file_info.h中定义
              status = apr_dir_make(content->key.data, 0x0755, options->pool);
              if (status != APR_SUCCESS && !APR_STATUS_IS_EEXIST(status)) {
                  printf("mkdir: %s failed, status: %d\n", content->key.data, status);
              }
          } else {
              //下载对象到本地目录，这里默认下载在程序运行的当前目录
              s = cos_get_object_to_file(options, &bucket, &content->key, headers, params, &file_name, &resp_headers);
              if (!cos_status_is_ok(s)) {
                  printf("get object[%s] failed, req_id:%s\n", content->key.data, s->req_id);
              }
          }
      }
      is_truncated = list_params->truncated;
      marker = list_params->next_marker;
  }
   //销毁内存池
  cos_pool_destroy(p);
}
int main(int argc, char *argv[])
{
  // 通过环境变量获取 SECRETID 和 SECRETKEY
  TEST_ACCESS_KEY_ID     = getenv("COS_SECRETID");
  TEST_ACCESS_KEY_SECRET = getenv("COS_SECRETKEY");
    if (cos_http_io_initialize(NULL, 0) != COSE_OK) {
     exit(1);
  }
   //set log level, default COS_LOG_WARN
  cos_log_set_level(COS_LOG_WARN);
   //set log output, default stderr
  cos_log_set_output(NULL);
   test_download_directory();
   cos_http_io_deinitialize();
   return 0;
}

简单操作

下载对象

功能说明

下载一个对象至本地。该操作需要对目标对象具有读权限或该目标对象已对所有人都开放了读权限（公有读）。

方法原型

cos_status_t *cos_get_object_to_file(const cos_request_options_t *options,
                                   const cos_string_t *bucket, 
                                   const cos_string_t *object,
                                   cos_table_t *headers, 
                                   cos_table_t *params,
                                   cos_string_t *filename, 
                                   cos_table_t **resp_headers);

参数说明

返回结果说明

示例：普通下载

#include "cos_http_io.h"
#include "cos_api.h"
#include "cos_log.h"
// endpoint 是 COS 访问域名信息，详情请参见 https://www.tencentcloud.com/document/product/436/6224 文档
static char TEST_COS_ENDPOINT[] = "cos.ap-guangzhou.myqcloud.com";
// 开发者拥有的项目身份ID/密钥，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char *TEST_ACCESS_KEY_ID;                //your secret_id
static char *TEST_ACCESS_KEY_SECRET;            //your secret_key
// 开发者访问 COS 服务时拥有的用户维度唯一资源标识，用以标识资源，可在 https://console.tencentcloud.com/cam/capi 页面获取
static char TEST_APPID[] = "<APPID>";    //your appid
//the cos bucket name, syntax: [bucket]-[appid], for example: mybucket-1253666666，可在 https://console.tencentcloud.com/cos5/bucket 查看
static char TEST_BUCKET_NAME[] = "<bucketname-appid>";
// 对象键，对象（Object）在存储桶（Bucket）中的唯一标识。有关对象与对象键的进一步说明，请参见 https://www.tencentcloud.com/document/product/436/13324 文档
static char TEST_OBJECT_NAME1[] = "1.txt";
static char TEST_DOWNLOAD_NAME[] = "download_test3.dat";
void log_status(cos_status_t *s)
{
  cos_warn_log("status->code: %d", s->code);
  if (s->error_code) cos_warn_log("status->error_code: %s", s->error_code);
  if (s->error_msg) cos_warn_log("status->error_msg: %s", s->error_msg);
  if (s->req_id) cos_warn_log("status->req_id: %s", s->req_id);
}
void init_test_config(cos_config_t *config, int is_cname)
{
  cos_str_set(&config->endpoint, TEST_COS_ENDPOINT);
  cos_str_set(&config->access_key_id, TEST_ACCESS_KEY_ID);
  cos_str_set(&config->access_key_secret, TEST_ACCESS_KEY_SECRET);
  cos_str_set(&config->appid, TEST_APPID);
  config->is_cname = is_cname;
}
void init_test_request_options(cos_request_options_t *options, int is_cname)
{
  options->config = cos_config_create(options->pool);
  init_test_config(options->config, is_cname);
  options->ctl = cos_http_controller_create(options->pool, 0);
}
void test_download_object()
{
  cos_pool_t *p = NULL;
  int is_cname = 0;
  cos_status_t *s = NULL;
  cos_request_options_t *options = NULL;
  cos_string_t bucket;
  cos_string_t object;
  cos_string_t file;
  cos_table_t *resp_headers = NULL;
   //创建内存池
  cos_pool_create(&p, NULL);
   //初始化请求选项
  options = cos_request_options_create(p);
  init_test_request_options(options, is_cname);
  cos_str_set(&bucket, TEST_BUCKET_NAME);
   //获取对象
  cos_str_set(&file, TEST_DOWNLOAD_NAME);
  cos_str_set(&object, TEST_OBJECT_NAME1);
  s = cos_get_object_to_file(options, &bucket, &object, NULL, NULL, &file, &resp_headers);
  if (cos_status_is_ok(s)) {
      printf("get object succeeded\n");
  } else {
      printf("get object failed\n");
  }
   //销毁内存池
  cos_pool_destroy(p); 
}
int main(int argc, char *argv[])
{
  // 通过环境变量获取 SECRETID 和 SECRETKEY
  TEST_ACCESS_KEY_ID     = getenv("COS_SECRETID");
  TEST_ACCESS_KEY_SECRET = getenv("COS_SECRETKEY");
    if (cos_http_io_initialize(NULL, 0) != COSE_OK) {
     exit(1);
  }
   //set log level, default COS_LOG_WARN
  cos_log_set_level(COS_LOG_WARN);
   //set log output, default stderr
  cos_log_set_output(NULL);
   test_download_object();
   cos_http_io_deinitialize();
   return 0;
}